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I’m interested in nutrition and weight gain because I don’t understand how I am so skinny.

At almost 5’11,” I have weighed between 135-143 pounds since I was a freshman in high school despite having an extremely unhealthy diet by popular standards for most of that time. My regular dinners were pasta, pizza, and cheeseburgers, but it was the enormous amount of sugar that should have really put me over the edge. I don’t think people can really understand how many Chew Chips Ahoy’s cookies, Freihofer’s donuts, Tollhouse cookie dough, and brownie mix I have eaten over the years. During particularly bad times I would estimate that 40-60% of my daily calories came from these heavily processed sugary snacks.

At the same time, my energy out-put has been vanishingly low. I used to play soccer, lacrosse and other more strenuous sports, but in high school I did track and skiing, neither of which are particularly grueling, and for neither of which I put forward more than sub-minimal athletic effort. I also never play sports casually. But I’m on my computer or video game console for probably 8-10 hours per day on average, even when I was in college. I have generally made no other effort to move any more than I had to throughout my life.

And yet my BMI at this moment is 19.2, which puts me in the “Normal” category from 18.5-25, and just barely above “Underweight.”

What is my body doing with everything I put in it? How do I consistently dispose of so many calories with such little activity? How am I not fat?

I’m not alone in doubting the conventional wisdom of the nutrition field. Most health-conscious Americans have developed an automatic skepticism to health claims. It seems like every other week a new study comes out that claims chocolate/coffee/milk/kale/acai berries cases weight gain/loss, stronger/weaker bones, and cancer growth/remission. Fad diets rise and fall, “health” foods and chains with contradictory claims have gained ground, but Americans continue to gain weight.

We need some sort of principles to guide our diets. We need to know what to eat and what to avoid, how much to eat, when to eat, where to eat, etc. But nobody seems to have a clear understanding of any of that. I don’t think nutritionists even have a stable definition of “healthy.” Is the standard of health, longevity? Some combination of biometrics like blood pressure and heart rate? Physical strength? Propensity to get sick? Some sort of intangible feeling of wellness?

I don’t even understand how nutritional studies can be effectively done. Don’t a billion different factors affect how your body processes any given nutrient? Between biological, genetic, and environmental factors, as well as all of their concurrent interactions, how could a researcher ever possibly control enough variables to isolate a causal effect of a particular food? Sure, there are instances where a food’s impact is overwhelmingly powerful (like poison), but otherwise I just can’t imagine how a single experiment could eliminate enough outside interference to definitively claim that say, red meat increases one’s risk of developing colon cancer.

It’s possible that I’m just utterly ignorant on this matter. Maybe researchers never actually try to make such definitive statements and it’s the media’s fault for reporting research results in such a way. Or maybe there really are great experimental methods for restricting enough variables to establish very broad or very specific causal chains. But whatever confidence should exist in nutritional studies, to me it is certainly not warranted by how nutrition has been taught to me in school or proscribed by the government. Nutrition studies in their current form seem like a shit show of sporadic and contradictory claims that cannot possibly provide adequate guidance to health conscious individuals.

When I first became explicitly interested in nutrition in college, I conducted some experiments on myself entirely out of curiosity. Nassim Nicholas Taleb’s work introduced me to the Paleo diet, which sounded logical and cool to me. Human beings have existed in their current physical form for about 100,000 years, yet agriculture has only been around for 10,000 years (at earliest) and modern diets have only existed for 50-100 years. Therefore we should assume that humans are nutritionally optimized to pre-modern diets and we should eat as closely to that ideal as possible.

I found the experience enlightening because it changed my understanding of what food can do to your body (beyond effecting your weight). It’s amazing how differently you feel when you change your diet. There is no more official or scientific way to say it, but if you eat paleo for a week you will physically feel better. You will be feel lighter, more energetic, and more attentive. My sense of hunger became more sophisticated – I could feel when I was hungry for fat, sugar, or heavy carbs specifically (I never felt hungry for vegetables). On the negative side, I went through severe sugar withdrawal which was far worse than I thought it would be, and I had trouble eating enough calories to maintain my weight.

Of course I can’t extrapolate too much about the nature of nutrition from my sample size of one, but at the very least I realized that how food effects your body is far more complicated that I used to think.

So I decided to try to investigate the topic on my own. Admittedly, my biology knowledge tops out at getting a 4 on my AP Biology test in 12th grade and watching every episode of House M.D, so I’m probably not capable of carefully evaluating nutritional studies. My best option is to look at the top nutritional theories today and compare them both to each other and my own personal experiences.

After some Googling I found Dr. Stephan Guyenet and Gary Taubes to serve as good representatives of the current divide in the nutrition field. Guyenet stands for the consensus view that weight gain and loss is fundamentally an energy-balance issue which has been thrown out of whack by the modern world. Gary Taubes represents an unorthodox and somewhat heretical viewpoint that weight changes are an almost purely hormonal product which are exacerbated by carbohydrate-rich diets.

Dr. Stephan Guyenet’s Argument

You get fat because you eat lots of food which is highly rewarding to your brain which overrides your in-built weight regulation system, and eventually can cause your body to fully acclimate to, and even defend a heavier weight.

The First Law of Thermodynamics states that energy can never be lost or created, only transferred. Your body is capable of absorbing, storing, and consuming (exporting) energy in the form of calories. Therefore fundamentally all weight changes are products of the alteration in the body’s net energy balance. If you take in more energy by eating then you spend by moving in a day, you will gain weight that day. If you take in less energy than you spend by moving, you will lose weight that day. The “type” of calorie you eat, whether it be carbohydrates, fat, or protein, doesn’t matter in and of itself in terms of its effect on weight change. A calorie is a calorie is a calorie. This concept is referred to as CICO – Calories In, Calories Out. Simple.

However, to prevent your body from awkwardly lurching between emaciation and obesity on a weekly basis, we have strong internal mechanisms to keep our weights at remarkably steady states. A part of our brain located at the brain steam called the “lipostat” deploys hormones throughout the body to regulate our appetites in response to changes in weight gain. (If you remove all of a rat’s brain besides the brain stem, that rat will be entirely dysfunctional but it will still eat normal meal portions and control its own weight).

Most healthy people are really good at maintaining their weight at a pre-designated steady state, as has been demonstrated in study after study. If you force someone to overeat, not only will their body strongly resist it by shutting down the appetite during the meal, but the body will continue to suppress the appetite indefinitely until the individual’s weight falls to normal levels. Likewise, if a person is starved for a week and then given access to as much food as he wants, he will engorge himself until he reaches his pre-starvation weight and then his appetite will return to pre-starvation levels.

This internal weight regulation is steered through the production of the hormone, leptin. The more leptin you have floating around in your body, the less hungry you’ll be, and vice versa. Before meals you will typically have low leptin levels. As you eat, your leptin levels will rise, thereby not only making you less hungry but also reducing your taste satisfaction with eat bite. Once your leptin levels reach a certain height you will feel no hunger and stop eating. Then they will gradually fall until you are ready to eat for your next meal. Unfortunately, externally injecting huge doses of leptin into people doesn’t seem to work as a good appetite suppressant for some reason.

Another way your body regulates weight is through changes in your body’s use of calories. “Non-activity exercise thermogenesis,” or NEAT, is the level at which your body passively burns calories. Your body will turn up or down its NEAT level depending on whether you are consuming more or less calories than your steady state requires. So if you under eat you will feel low energy and not move much. If you overeat and you aren’t maintaining a level of unusually high physical exertion, NEAT typically takes the form of fidgeting. The most extreme fidgeters can burn up to 700 calories per day.

What complicates matters a bit is that our leptin doesn’t work in a vacuum. Rather, it directly competes with our enjoyment of food. If a food is particularly rewarding to your brain, you may very well override your leptin levels and keep eating passed the point your lipostat wants you to.

It turns out that there are many, many different food factors which can cause this too occur. The most obvious factor is pleasurable taste, as in the case of sweet, savory, and some meat-flavored foods. If you’ve ever eaten an enormous dinner and felt super-full, but then saw a sweet, delicious-looking desert and suddenly found room in your stomach to keep eating, your reward centers for eating tasty food is overriding your leptin levels. Calorically dense foods seem to have the same effect, which is why you can generally always eat more bread, pasta, dough, and chocolate, but not more vegetables (even the tasty ones like avocado). The same applies to foods with little water, like crackers and processed foods. Ditto for foods with secondary enjoyment benefits like alcohol or caffeine. Most surprisingly of all, food variety also has this effect. Our cavemen ancestors didn’t sit down to a meal with four different food groups, so apparently our modern brains have difficulty figuring out how to calculate how much leptin it should produce in those situations, and often undershoots its mark. If that doesn’t sound right to you, try a few meals where you only eat one type of food and see what happens.

The more you eat past your leptin levels, the more leptin your lipostat will pump out. Eventually your body will get used to this new higher level of leptin and your lipostat will embrace a new higher-weight steady state to maintain. If you continue to push past this point to the level of obesity, you will literally damage your lipostat so that it has trouble ever reducing its leptin levels in the future. To be fair, this last point has only been proven in rats, but it’s also probably true in humans. Basically, fat people are brain damaged.

Observational data of existing pre-modern tribal societies in South America and Africa reveal utterly unrestricted eating habits which nevertheless produce almost exclusively thin bodies. Despite different tribes getting their calories from entirely different sources (some eat predominately fat, others predominately carbs), all of the tribes tend to engorge themselves on any available calories they find. Of course, they don’t always find calories and sometimes go days without eating, but even when food is plentiful, pre-modern people’s bodies seemingly have no trouble maintaining low weights without any conscious foresight.

In contrast, despite a national cultural obsession with weight-loss, dieting, and exercise, Americans get fat because they live in an environment designed to overload their senses with unnaturally rewarding foods. Every gas station has dozens of candy bars, pastries, alcoholic beverages, and soft drinks on display. Televisions blare commercials for food all day, especially to children. Even the smallest towns have dozens of restaurants catering to every food variety imaginable. At a big city like NYC or LA you can eat the fattiest food from almost any country or culture on earth.

But most importantly of all, our food has never been more heavily designed to provide the leptin-overriding rewards that make us fat. Just as video games, social media, and porn can damage our natural stimulation thresholds through their sheer overwhelming addictiveness, modern processed food overrides our lipostat. Food companies have spent decades developing every tastier and more calorically dense foods. The food producers know cheeseburgers, Twinkies, and Doritos are addictive, so they compete with one another to make them as appealing to consumers as possible.

The result is a toxic environment which drives even the most conscientious individuals to overeat. Kids eat giant bowls of sugary condensed grain every morning. Adults buy 500 calorie coffee products for an afternoon energy burst. At any time during any day you can drive to the nearest gas station or convenience store and engorge yourself on the best tasting foods in the world at the lowest dollar-per-calorie rate on earth. It’s no wonder that we’re all fat.

To be slightly more specific, you can go down a checklist of factors which make food more appealing to your reward centers, including sweetness, savoryness, meat flavor, calorie density, low water levels, alcohol, caffeine, processed food, etc, and avoid those factors. You can also take note of which of those factors especially effect you and avoid them. But at the end of the day it really does come down to making your meals less enjoyable.

The easiest way to do this is to target meal “satiety” over meal “satisfaction.” That is, you eat foods which have a balance of the above factors which make them somewhat enjoyable but still not rewarding enough to overpower your leptin. For instance, potatoes somehow have the right combination of factors to make them a great diet food.

According to Dr. Stephan Guyenet, why am I so skinny?

I have an extremely strong lipostat which targets a low weight point. This may explain why I often take long breaks between meals and why I fidget so much (and maybe why I have trouble sleeping). This is most likely a product of my genetics.

I am apparently a victim of many of the strong leptin-overpowering factors Guyenet discusses. I do engorge on sweet and calorically dense food. I constantly find myself full after dinner but then somehow ready to pack in hundreds of extra calories of my preferred snacks. Apparently my lipostat heroically holds my weight in check anyway.

Gary Taubes’s Argument

You don’t get fat because you eat a lot, you eat a lot because you’re getting fat. Weight gain is fundamentally a hormonal issue. Carbohydrate consumption stimulates the production of insulin which tells your body to absorb and store fat, thereby making you gain weight. Almost no other factors have any effect on your long-term weight.

Yes, you will gain weight if your body takes in more calories than you consume, but saying that’s how you get fat is like saying you can get rich by putting more money into your bank account than you take out. That’s technically true but a pointless tautology which doesn’t actually give me any useful advice on how to get rich.

Babies more than double in size during the first year of life. When men go through puberty they lose their baby fat and gain muscle. When women go through puberty they gain fat, especially in the waist, thighs, and breasts. People can have massive, cancerous tumors grow in their organs. Technically, all of these physiological events require a positive CICO count, yet it would be quite bizarre to attribute a baby’s growth, fat changes during puberty, or cancer to eating more calories than one consumes. Clearly all three scenarios are the product of specific hormonal imbalances (cancer might be something else, I’m not sure) that trigger adjustments in the body’s accumulation and distribution of mass, to which the body’s general CICO count is at best a distant variable.

All of the previous paragraph’s examples could be negated by a theoretical negative CICO scenario. If a child is starved in its infancy, it will face stunted growth both in physical stature and organ development. Likewise, if children go through malnourishment during puberty they may very well be delayed in developing mature sex characteristics. And theoretically you could even prevent a tumor from growing through caloric intake restriction, though I imagine the individual would have to be at a point of starvation for that to occur. But in all of these cases, despite the body undergoing a change in weight and fat accumulation, clearly the primary causal factor of these events is far beyond CICO.

So if babies, teenagers, and cancer-ridden individuals all undergo rapid transitions in mass accumulation due to hormonal changes, why should regular obese people be any different? They aren’t.

People become fat because of insulin, a hormone secreted by the pancreas, and its subsequent regulation of the enzymes, lipoprotein lipase (LPL) and hormone sensitive lipase (HSL). Insulin is triggered by eating, seeing, or thinking about carbohydrates. Once it enters the blood stream, insulin encourages your fat cells to absorb and store energy in the form of long-term fat deposits. If you eat too many carbohydrates over a long period of time or have certain genetic predisposition, you develop “insulin resistance” which requires your body to produce ever increasing amount of insulin in response to carbs and makes you ever fatter. Here’s how it works:

Whenever you’re not eating your fat cells slowly release either fat (ketos) or carbohydrates (glucose) particles into your blood stream to provide energy for your ordinary body operations. When you eat carbohydrates, sugar floods your blood stream and becomes the new operational energy. But having too high blood sugar levels makes your blood too thick to flow and can kill you. So insulin is pumped into your blood to lower blood sugar levels by making fat cells suck up the sugar for storage until the blood sugar levels fall to a healthy level. At that point your fat cells will resume their regular export of energy into the blood stream.

Essentially your fat cells are like a wallet and the calories are like money. Throughout the day you regularly take small amounts of money out of your wallet until you need to go the ATM for a big cash infusion. Likewise, throughout the day your fat cells release small amounts of energy until you eat and replenish their stores.

LPL is an enzyme that sticks out of fat cells and sucks energy into cells (both fat and muscle cells). The reason women develop larger thighs, butts, and breasts than men is because they have more LPL in those regions. HSL is an enzyme within fat cells which breaks down triglycerides (the stored form of fat energy) into fatty acid components which are small enough to escape flat cells and reenter the blood stream as energy. Insulin simultaneously activates LPL and suppresses HSL, thereby ensuring that we store more fat as tissue and consume less fat as energy. So if I have to continue the wallet metaphor, I guess you can say that insulin makes your wallet very sticky – it’s easy to stick more money into it, but hard to tear money out of it.

So if you’re a normal, healthy, average weight human, that’s not a big deal. You eat carbohydrates, your body pumps out insulin, your fat cells store more energy, and then you slowly release that energy throughout the day whenever you’re not eating. As long as you burn more calories throughout the day then you stored, you should maintain a steady body weight (though that is a lot more complicated than it may seem as I’ll explain later).

But what if you’re not a normal, healthy, average weight human? What if you enjoy eating 25 Chewy Chips Ahoy chocolate chip cookies in one sitting and do so regularly. Then eventually, for not entirely understood reasons, fat cells can develop a resistance to the effects of insulin, thereby prompting your body to produce ever higher levels of insulin to complete the same level of glucose up-take in the fat cells. This is called “insulin resistance.” Type 2 Diabetes is a severe form of this resistance.

If you’re insulin resistant and eat a bunch of cookies, the first round of insulin secretion won’t be enough to lower your blood sugar to a safe level. So your body releases another round of insulin. And another. And another. Etc. Every time the insulin is released your LPL enzymes suck up more energy into the cells (though not as much as normal, insulin sensitive fat cells) and HSLs make sure the new energy is packaged as long-term fat deposits.

And then to make matters worse, the sheer volume of insulin injected into your blood stream may very well over-shoot its mark and dip your blood sugar too low. This essentially makes your body starved for energy to run its normal systems. You become fatigued, dizzy, and hungry. And so you eat more (delicious, calorically dense) carbohydrates and restart the cycle.

You gain weight because insulin tells your body to gain weight. There is nothing else practical you can do to your body to make it gain weight in the long run than to induce insulin production in your body. Likewise, there is nothing practical you can do to lose weight besides avoiding carbohydrates.

“What if I exercise every day and don’t increase my caloric consumption. Won’t that help me lose weight?”

No. Using more energy through physical activity simply increases your body’s natural demand for energy, thereby making you hungrier. You really do “work up an appetite” equal to the calories you burned. Plus you’d be shocked at how few calories exercise actually burns.

“Ok, but what if I force myself to eat 10,000 calories per day of non-carbohydrates? Won’t I get fat by doing that?”

Try to eat 10,000 calories of filet mignon in a day. Hell, try to eat 5,000 calories of steak in a day. Or even 3,000 calories. You will probably notice that it’s extraordinarily difficult to do, if not impossible. It doesn’t matter how tasty the food is, overeating fat is almost impossible. The simple hormonal explanation for this is that eating pure steak will only trigger miniscule levels of insulin (due to the protein content) and therefore your fat cells won’t be receptive to new energy and you won’t be hungry after eating a moderate amount of steak.

On the other hand, try to eat 10,000 calories of bread, potatoes, or cookies in a day. The sheer size of it will be hard, but dramatically less so than with steak. This is because the repeated insulin spikes will crash your blood sugar and make you hungry. Even if you aren’t too insulin resistant, the sheer volume of carbs would make it possible to eat that much with training (think of competitive eaters or Olympic athletes).

“But what if I force myself to eat 2,500 calories of steak per day and then lie in bed all the time so that I purposefully expend as little energy as possible? Won’t I gain weight?”

You will probably lose weight. First, with low insulin levels, your body will withdraw more and more energy from fat cells into the blood stream. This will reduce your body’s need for food and kill your appetite. Second, your low energy expenditure will reduce your body’s need for energy, thereby making it easier for the existing fat stores to cover daily energy use, thereby further suppressing your appetite. So eating 2,500 calories per day of steak would probably be impossible without staggeringly high willpower.

“Alternatively, what if I only eat 500 calories of carbohydrates and run ten miles per day? Won’t I lose weight by doing that?”

Maybe at first. It depends on your body’s natural need for calories. If 500 calories is sufficiently low, then yes you will lose weight. But you will also feel like you are starving to death. It will be nearly impossible to maintain this level of suffering for long, again, without absurdly high willpower. Plus your energy levels will crash so exercise will be extremely difficult. And whatever exercise you do manage will only increase your body’s demands for energy, thereby making you even hungrier.

Alternatively, if you are light enough that 500 calories per day puts you over a certain threshold, then no, you won’t lose weight. You will simply deprive your body of energy and in response you will feel like you have no energy and be unable to run at all, let along run ten miles per day. In that case, you will probably gain weight anyway and feel hungrier than you can imagine.

“But what if I really do have insanely strong will power? Can’t I force myself to eat a ton of steak calories or run despite my low energy or resist eating despite starving, and just power through all of this hormonal stuff until I lose or gain weight like I want to?”

Yes. You could also hold your breath until you passed out. But even if I offered you a lot of money, you would almost certainly fail to do so, especially if you had to do it repeatedly and indefinitely. So it is with attempts to override hormones with CICO.

This is why every large-scale diet study ever shows that pretty much every diet will succeed in the short-term and then fail in the long-term. When you are super hyped up about losing weight, you can force yourself to exercise and starve yourself until you negative CICO your way to a lower weight. Eventually the suffering will be so bad that you will cheat on your diet and rapidly regain weight as your exhausted body tried to reduce energy expenditure and your emaciated fat cells try to regain their weight.

You can call this a “failure of willpower” but that’s cruel. Empirically almost no one can override their hormones and metabolism for long. Contestants on The Biggest Loser pretty much always gain back their weight. Dieters nearly always fail. There are occasional success stories (you may know a random person who pulled off a long term weight loss) but those are instances where the dieter either used the objectively superior low carb diets (like Keto, Atkins, or Paleo) or he accidentally triggered some sort of hormonal readjustment in his body which lowered his body’s naturally inclined weight, which is good for him, but also an idiosyncratic anomaly which can’t be generalized to the greater population.

According to Gary Taubes, why are Americans so fat?

Americans eat enormous quantities of carbohydrates and especially sugar. Or rather all Westerns do, but Americans especially do.

Humans have existed in their current biological form for about 100,000 years but we have only had agriculture for about 10,000 years, and significantly less long in many places. According to widespread analysis of pre-modern tribal diets, humans used to get the majority of their calories from fat, a decent amount of their calories from protein, and a small minority of their calories from carbohydrates. There were no loafs of bread, let alone 25-packs of Chewy Chips Ahoy chocolate chip cookies. People mostly ate meat, and occasionally nuts and vegetables, and even less so fruit. There was also no such thing as portion control – they would engorge themselves on animal meat until they couldn’t move.

And yet pre-modern humans were far healthier than modern humans on a physiological level. Yes, premodern humans didn’t have modern medicine so they regularly died of injuries and infectious disease, but they had non-existent rates of modern, Western diseases like cancer, heart disease, diabetes, obesity and gout. Granted, the connections between some of these diseases and carbohydrate consumption isn’t quite clear yet on a biological level, but they are undoubtedly correlated with the conversion of pre-modern diets to modern diets.

There are dozens of examples from around the world of population groups adopting modern diets and suddenly becoming extremely unhealthy. Modern Native Americans have the highest rates of diabetes and obesity of any ethnic group in America. Australian Aborigines suffer the same problems.

But what’s especially notable are instances when the modern diet is first introduced at low quantities. If you look at the health records of early Native American reservations or introductions of numerous South American tribes to Western cuisine, you’ll find that somehow these populations simultaneously suffered from starvation and obesity. Health workers noticed that often obese mothers would nurse emaciated children. Either these were the worst mothers in the world or they demonstrate the unique unhealthiness of Western diets. Basically the mothers who needed fewer calories to survive became obese because all they ate was starch and sugar, while the fast growing babies who needed more calories weren’t getting enough to survive and so they starved. In reality, both the mothers and children were malnourished, but because of the way insulin effects the body, the mothers looked to be the exact opposite of malnourished simply because their bodies were directing all of their meager energy intake into fat deposits.

So Americans are fat because way too much of our diet is dependent upon carbohydrates and sugar. We eat the ultimate form of the Western diet. East Asians eat lots of rice and wheat, but very little sugar and tons of fat through oil. Plenty of Europeans eat a lot of grains and thus also suffer from high rates of Western diseases compared to the rest of the world, but they also support their diet with lots of fat (what type of fat varies by region).

But Americans have been trained to be anti-fat for decades. From roughly the 1970s-2000, Americans were sold the idea that eating fat causes heart attacks. The primary basis for this assertion was a horribly flawed study which claimed to track lower obesity rates in European countries with less fat consumption, though in reality the data was heavily cherry picked. Nevertheless, Americans embarked on a low fat craze which saw many foods lose most or all of their fat content in exchange for carbohydrates. Likewise, pork and beef consumption was traded for lean chicken meat and Americans began exercising more than any Western country.

The result was 30 years of skyrocketing obesity and diabetes while Americans ate more carbohydrates and less fat (protein stayed about the same). Slightly more difficult to demonstrate statistically but also probably true, is that Americans are suffering from worse rates of heart disease and cancer than ever before. Unfortunately (from a purely statistical standpoint), the decline in smoking rates and increase in exercise may be confounding variables which screw up the trends.

According to Gary Taubes, how do you lose weight?

Don’t eat carbohydrates, especially sugar. That’s it. You can eat anything besides that, and as much as you’d like.

By not eating carbohydrates you avoid raising your insulin levels and so your body won’t increase its fat stores. This will also make your fat cells more sensitive to insulin in the long run which will reduce the fattening effects of carbohydrates. You’ll also find that without your periodic insulin bursts and subsequent blood sugar crashes, you’ll end up less hungry throughout the day. However, this probably won’t lower your energy levels because your body will just ransack existing fat cells for its daily energy use.

For many people, simply cutting out carbs will cause their weights to immediately crash, but for some people it’s a bit more complicated. If your body has very high insulin resistance, it may very continue to produce high insulin levels even after you stop eating carbs. You will still probably lose weight, but slowly at first, and maybe not at all after a few weeks as your body fights to maintain its weight levels. But eventually you should break through this wall as your insulin sensitivity increases.

Additionally, if you immediately cut out all sugar you may very well feel like you are starving to death for a week or two even if you eat tons of fat. This is because your body is literally addicted to sugar by the same biochemical feedback loops as you could be (or are) addicted to cocaine. You will go into withdrawl and crave sugar throughout the day. You’ll feel extremely hungry, but no foods will satisfy you except sugar. Eventually this will pass but it’s rough to get through.

According to Gary Taubes, why am I so skinny?

I probably have a genetic predisposition to extreme insulin sensitivity. No matter how much sugar I dump into my veins, my insulin rapidly packs the energy away in my fat cells and brings my body back to a state of slow energy release so I can start burning off calories again.

Who do I agree with?

I slightly lean towards Taubes. They both make a lot of good arguments which resonate with my personal experiences. They both have a lot of good laboratory and wider population data to support their claims. I find it impossible to really dig into the data with my limited scientific training because I don’t have the expertise to spot whatever flaws might exist. Often Guyenet and Taubes will directly contradict each other and offer evidence in the forms of experiments on the same topics that come to completely different results. Of course, figuring out how to get around this issue is pretty much the entire reason why I started this project in the first place, so I’ll try to explain my evaluation of both arguments in detail.

Guyenet’s description of the connection between rewarding foods and hunger perfectly describes my entire dietary life. I have gone through weeks where I would eat a small lunch or dinner, feel full, and then gorge myself on cookies or donuts with seemingly no possibility of satiating myself. If something tastes good enough, I’ll never want to stop eating it. Likewise, Guyenet captures why diet failure rates are so high: walking past MacDonalds and pizza to buy a fresh salad takes far more will power than people can muster indefinitely.

Taubes’s description is closer to my understanding of nutrition before this project. He even states in a Q&A section at the end of the book that he is something of a Paleo ally. What Taubes captures better than Guyenet is how eating different food effects your body. Guyenet basically believes a calorie is a calorie, and though he might also think nutrients effect how one processes food in the short term, he doesn’t go into that in the book. This strongly contradicts my experiences, as well as the experiences of some friends and a massive online community of Paleo/Atkins people. Sure the placebo effect could explain some of this experience, but I think it’s too strong to completely blame on psychological factors. I encourage anyone who doubts that carbohydrates have a specific (and largely negative) effect on their wellbeing to try not eating carbs for a week and see how they feel. Or better yet, eat nothing but carbs for a week before that and notice the difference.

The primary reason it’s hard to pick between these two theories is that they strongly overlap where it counts the most. Guyenet blames our overeating on heightened hunger caused by rewarding food (and their cues) but it just so happens that nearly all highly rewarding foods are carb heavy. So do people get fat because they eat lots of carbs which spikes their insulin? Or do they get fat because carbohydrates are so delicious that they can’t but help eat a lot of them?

In sum, based on my personal experience experimenting with taking heavy loads of specific macronutrients, and by feeling the strong effects of those nutrients in the short and medium term, I find it hard to believe that in the long run a calorie is a calorie is a calorie. Guyenet’s arguments about how food reward drives hunger certainly have a lot of merit to them, but I can’t think of any non-carb based foods which provoke that insatiable drive for more calories like sugar and carbs do. Steak is one of my favorite foods in the world, and even though I have regularly eaten a pound of meat in one sitting, it never felt the same as eating a box of donuts, nor did it leave me as hungry a few hours later.

Of course this is just my subjective opinion based on my own lived experiences, but after doing the readings and thinking about it for a few days I lean towards Gary Taubes’s understanding of nutrition even though I think Guyenet’s views have great merit.

There are a few other minor components of both author’s arguments that are worth bringing up.

I agree with Taubes more on exercise. All of the personal and laboratory evidence I have seen suggests that most people drastically overestimate the calorie-burning potential of exercise. I distinctly remember first coming to this realization when I used to play DDR Max. I would sometimes play on the “Workout” mode where the game estimates your number of calories burned depending on your weight and how well you perform on a given song. I was always shocked to find that even during intense 3.5 minute songs, I would almost never burn more than 25 calories Even when I worked myself to sweat and exhaustion I found the results of my work were enough to be wiped out by a slice or two of bread. In addition, my MMA friends seem to turn their stomachs into black holes after every work out anyway.

Taubes supports my experience by pointing out that climbing a flight of stairs burns roughly 3 calories and claiming to have direct experimental data to suggest that exercising merely increases hunger proportionately and therefore has no serious effect on weight loss. On the other hand, Guyenet seems to take an ambiguous position that working out can cause an increase in appetite, but it’s unclear how much. I’m sure the appetite response is variable based on personal and environmental factors, but I’m more concerned about an individual’s ability to use exercise as a weight loss tool, and Tubes argues against that effectively.

I find both authors’ discussions on pre-modern societies rather weak, though Guyenet’s is worse. Both claim that pre-modern diets support their own positions, with Guyenet looking at two currently existing tribes which eat a variety of macro nutrients (including lots of carbs) while Taubes uses a list of 150 no longer existing tribes, nearly all of whom have heavily fat-based diets. I think what they both miss is the genetic distance between the particular tribes they examine and modern Americans. Guyenet’s two tribes are from Africa and South America, while Taubes’s tribes are from all over the world. Neither mention any consideration for the majority of modern Americans being decedent from Europeans whose premodern ancestors had distinct diets from their African, Asian, or South American cousins. Given that our bodies adapt to our environments, we should expect that Europeans are better suited to particular nutritional factors than others. For instance, East Asian populations have high rates of lactose intolerance compared to the more milk-friendly European population. I would even go as far as to make a low confidence speculation that pre-modern Europeans ate more meat than other pre-modern populations due to their respective climate conditions.

In addition to having diametrically opposed understandings of nutrition, Guyenet and Taubes serve as interesting intellectual counter-parts. Guyenet is a neuroscientist firmly rooted in the nutrition field’s consensus who focuses on the neurological drivers of hunger. He spends much of the book describing brain structures and (awesome) laboratory experiments describing removing parts of rat brains or even physiologically stapling rats together. In contrast, Taubes is a physicist who after gaining a reputation for debunking junk physics was called into the even more mistrusted field of nutrition to work his magic. After personally combining through the last 150 years of key research, Taubes concluded that the science was doing pretty well until the mid-20th century at which point it became out-right awful due to a mixture of incompetence and corruption.

Guyenet’s books and writing are more technical and jargon-laden, though still relatively easy to understand by the standard of neuroscience. Taubes has plenty of laboratory references as well, but puts more rhetorical weight on easily understood population studies concerning the broad relationship between an entire population’s health and the food it eats. Of the two, Taubes is the overall better writer (though Guyenet is by no means bad) and brings a much greater sense of energy to his claims. Taubes genuinely believes that the Western world has been headed down a disastrous path for the last 70 years due to the idiocy and immorality of nutrition researchers, and only a strong wake-up call can help everyone now. Guyenet seems to believe that Taubes isn’t quite a crack pot, but isn’t far from one either, and though Guyenet agrees that Americans have very unhealthy eating habits, he has a much less alarmist outlook.

I worry that Taubes has a seductive “renegade” air to his arguments that will unfairly persuade people to his side. I personally have a bad tendency to favor the arguments of outsiders and dissidents over the consensus, which is something I actively try to combat in my evaluations of positions in all domains. Within this debate, Guyenet can sometimes come off as a scowling, grumpy old man to Taubes’s free-wheeling, no-bullshit attitude.

2 thoughts on “Nutrition and Weight Gain”

I didn’t think there was so much disagreement in the two books as you did. Both books agree on the importance of hormones and eating foods that suppress the appetite. Both books would recommend cutting carbohydrates and especially sugar drastically.
I used to be a skinny person who could eat lost of junk food, but then I got married, got an office job, and started packing on the pounds.